The organization wants to establish an Islamic state in Palestine.
Hamas was founded in 1987 and originated as the Gaza branch of the Egyptian Muslim Brotherhood. It gained popularity which may be related to causes such as dissatisfaction with the more secular PLO organization/administration, social services provided by Hamas, and generally increasing religiousness in Muslim countries.
The organization won the 2006 Palestinian parliamentary elections but there has been no new parliamentary election since.
Israel initially supported the Hamas for reasons such as dividing the Palestinians. It has also been suggested that some Israelis who do not want a two-state solution prefer to have Hamas as the opposition for propaganda reasons.
Several countries and organizations have designated Hamas or just the military wing as a terrorist organization.
- How Israel helped create Hamas https://www.washingtonpost.com/news/worldviews/wp/2014/07/30/how-israel-helped-create-hamas/